Comparison of nuclear grade and DNA cytometry in breast carcinoma aspirates to histologic grade in excised cancers

Histologic grading of breast carcinomas is an important prognostic indicator of survival. An increasing number of patients, however, receive definitive therapy based on a fine-needle aspiration cytologic (FNA) diagnosis. This may limit standard grading techniques. Nuclear grade and DNA image cytometry in 35 FNA specimens taken from 34 patients were compared to DNA flow cytometry and histologic grade of the excised carcinoma using the Bloom system, as modified by Elston. Seven histologic grade I, 14 grade II, and 14 grade III infiltrating ductal carcinomas were studied. All histologic grade I carcinomas were diploid on the FNA specimen, and six showed nuclear grade I. Twenty-seven of 28 histologic grade II and III cancers had nuclear grades of 2 or 3. Twenty-five showed aneuploidy (19 cancers) or tetraploidy (6 cancers). The other three showed diploidy with increased S/G₂M (17-20%). Most of the tetraploid tumors were histologic grade II. Interobserver variability was greatest for nuclear grade (31%). Concordance between DNA studies by image analysis on the FNA and flow cytometry on the excised specimen was 80%. Both nuclear grade and DNA cytometry on FNAs can be used to distinguish most histologic grade I carcinomas from grade II and III cancers. DNA cytometry is more time-intensive but is less influenced by interobserver variation, and usually correlates with DNA flow cytometry on the excised specimen.